In Jainism, time is divided into infinite cycles, each consisting of two halves: Utsarpini (ascending half-cycle) and Avasarpini (descending half-cycle). Each half-cycle is further divided into six eras, called āras.

Santati Palan (संतति पालन) refers to the process of reproduction or procreation.

Santati Palan in the 4th Āra

The 4th āra is called the Duhṣamā-sukhamā (Dukhama Sukhama) — an era of increasing sorrow mixed with some happiness. According to Jain scriptures:

• In the 1st, 2nd, and 3rd āra, humans are born by autogenesis (spontaneous birth, called "upapāda"), and there is no sexual reproduction.
• From the 4th āra onwards, humans begin to take birth through sexual reproduction (Santati Palan via sexual union).
• In this era, people start forming families; mother, father, and children relationships are established.
• The system of marriage, family life, and social structure as we know it begins.
• Moral and physical strength declines compared to earlier eras.

Thus, Santati Palan in the 4th āra refers to the beginning of human procreation through sexual means, and the establishment of family and social order, as described in Jain Agamas and time-cycles philosophy.

References:

• Tattvartha Sutra (Jain canonical text)
• Jain Time Cycle (Kalachakra) explanations in Jain literature